This invention relates to improvements in apparatus for printing on fabrics, paper or similar material typically by means of the silk-screen process.
As is well known, the silk-screen process involves fixing the fabric to be printed upon a suitable surface, placing the silk screen on the fabric and then transferring the color to the fabric by means of a pliable roller or squeegee.
Where several colors are to be printed on the same fabric, an equal number of screens are used successively. This creates the problem of obtaining good registry of the various colors which form the design, numerals or letters being printed. Any solution to the problem has to be consistent with maximizing production rates.
The new apparatus, which achieves good registry of colors at high production rates, will be described in connection with the process of printing numerals on sportswear such as jerseys worn by football players. In particular, the apparatus will be described in connection with the process of printing numbers of one color on the fabric of jerseys and then printing a border of another color at the edge of the first printing so that the numeral is defined by a basic broad area color and a border or rim of another emphasizing color.
Some of the characteristics of the new apparatus to be described herein are generally known as exemplified by U.S. Pat. No. 2,613,595 and U.S. Pat. No. 3,427,964. U.S. Pat. No. 2,613,595 has a circularly arranged group of platens lying in a single plane for supporting fabric or other sheet material which is to be printed on with the silk-screen process. A group of silk screens are mounted for being pivoted toward the platens and for being indexed generally circumferentially to enable printing as many colors on the fabric as there are screens in the group. The screen frames are pivoted individually to a horizontal position for printing and back to an angulated position for indexing or rotating to the next work piece.
U.S. Pat. No. 3,427,964 has several platens on a revolving carriage and lying generally in a horizontal plane. Several platens are carried on another rotating support which is adjacent the carriage and rotatable about the same axis. The rotating support carries several pivotally mounted silk screen frames which are arranged at right angles to each other and which may be used to print several colors consecutively or a single color on a plurality of work pieces.
The above discussed apparatus and apparatus made by applicant heretofore are characterized by having the printing screens arranged in a common plane or single tier. This prohibits achieving certain new functions and objectives efficaciously. A use of the new apparatus is to print large numerals, for instance, on the front or rear of a jersey or other garment in one color and then apply a well registered border, rim or outline of a different color to the basic numeral. Another use is to print numerals on the shoulders or arms of a jersey in one color and to print a border of a different color on these numerals too. The problems of doing this without unsatisfactory registry are evident when one realizes that ten rather large silk screens bearing the digits 0 to 9 are required to produce all of the basic two digit numbers up to 99 and another ten screen frames are required for applying the different colored outlines or rims to these numbers. Heretofore, the need for using the total of twenty screens which are required for this procedure would have dictated use of more than one machine which means that more floor space would be required and that the total investment would be higher than if only one machine were needed as in accordance with the present invention.